But what is BMI? And should we still be using a system designed in the early 1800s?

BMI was created by Belgian statistician Adolphe Quetelet around 1830 as a measure of obesity and adopted by the British government in an effort to promote healthy eating.

It is calculated by dividing your weight in kilograms by your height in metres, then dividing the answer by your height again. This ratio is then compared to an index chart (known as the Quetelet index, main picture) to see whether you are underweight (a score of under 18), normal (18.5-24.9), overweight (25-29.9) or obese (over 30).

Albrecht is 1.5m tall and weighs 66kg – giving her the reading of 29. Accordingly, the nurse told her to exercise more and limit herself to 1,000 calories per day – just half the recommended number for a woman. For a competitive athlete, this was not good advice.

‘The last thing someone like Anita needs to do is restrict herself to 1,000 calories a day,’ says Caroline Finucane, health editor at NHS Choices.

‘Muscle cells need more energy to maintain than fat cells, so she’s already burning calories like there’s no tomorrow. Taking into account her fitness, waist measurement and factors such as cholesterol level and blood sugar would have given a much more accurate picture.’

Finucane says for most adults BMI is a quick and simple way to check whether you need to take action. But she admits it’s not perfect and doesn’t work for everyone.

‘It doesn’t distinguish between fat and muscle,’ she says, ‘so if you’re one of the few very muscly people like Anita, it could put you in an overweight category even if you have very little body fat. For this minority of people, BMI’s a fat lot of good.’

Although BMI might be a good rule of thumb for most, industry professionals say there are better alternatives for those who work out regularly.

‘BMI assumes we’re all made of the same proportion of fat, muscle and bone,’ says Pratik Sufi, weight-loss surgeon at the private Spire Bushey Hospital in Hertfordshire.

‘It’s not the most accurate measurement but because it is used so widely, it’s difficult to change. It’s something people recognise and trust, so to change it would take a huge concerted effort.’

So what’s the best way to see if you’re overweight? A cheap, simple and non-invasive method is to check your waist-hip ratio.

‘I don’t go by BMI because it doesn’t take into consideration 100 per cent of the population,’ says Greg Small, from the Register of Exercise Professionals. ‘But a waist-hip ratio is a good indicator of health and the risk of developing serious health conditions.’

In 2005, the Institute of Preventive Medicine in Copenhagen said people who carry weight around the waist (apple-shaped bodies) face more health risks than those who carry more weight around the hips (pear-shaped bodies).

And in 2008, The World Health Organisation published a report concluding: ‘The fundamental question of whether waist circumference and waist-hip ratio are useful measures for predicting disease risk was answered with convincing evidence.’

As an ex-professional rugby player, Small says his BMI puts him as morbidly obese. ‘For those working out regularly I wouldn’t use BMI,’ he says. ‘The waist-hip ratio is a much better assessment of where you are storing fat.’

Take your waist and hip measurements for a better indication of whether you are overweight (Picture: Alamy)

A better measure in your hips

With questions around the validity of using BMI to determine whether you are overweight, some experts favour measuring your waist-hip ratio.

The World Health Organisation (WHO) says the waist should be measured midway between the lower margin of the last palpable rib and the top of the iliac crest (the nobbly bit at the top of your hip). Hips should be measured around the widest portion of the buttocks.

Stand with feet close together, arms at the side and body weight evenly distributed, wearing little clothing. Each measurement should be repeated twice. If the measurements are within 1cm of each another, use the average. If the difference is more, repeat the measurements.

When you have both measurements divide the one for your waist by that for your hips to arrive at your waist-hip ratio.

WHO says a result of more than 0.85 for women and 0.9 for men shows abdominal obesity and carries health risks including type 2 diabetes and heart problems.